TESTING/LIN/dtrt02.f(3)

📦
version 3.12.1 · 3 versions
, in arch rolling

💖 NAME

TESTING/LIN/dtrt02.f — okay bestie, this is the manual page for the LAPACK testing subroutine dtrt02, also known as DTRT02 when it’s being loud. It lives under TESTING/LIN, and it is absolutely here to compute residual energy for triangular systems. No cap.

✨ SYNOPSIS

Functions/Subroutines

subroutine dtrt02 (uplo, trans, diag, n, nrhs, a, lda, x, ldx, b, ldb,
    work, resid)
    DTRT02

🦋 Function/Subroutine Documentation

subroutine dtrt02 (character uplo, character trans, character diag, integer
     n, integer nrhs, double precision, dimension( lda, * ) a, integer lda,
     double precision, dimension( ldx, * ) x, integer ldx, double precision,
     dimension( ldb, * ) b, integer ldb, double precision, dimension( * )
     work, double precision resid)
     DTRT02

💡 Purpose

DTRT02 computes the residual for the computed solution to a triangular system of linear equations op(A)*X = B, where A is a triangular matrix. The test ratio is the maximum over

norm(b - op(A)*x) / ( ||op(A)||_1 * norm(x) * EPS ),

where op(A) = A or A**T, b is the column of B, x is the solution vector, and EPS is the machine epsilon. The norm used is the 1-norm.

🎀 Parameters

UPLO

UPLO is CHARACTER*1. Specifies whether the matrix A is upper or lower triangular.

  • = 'U': Upper triangular
  • = 'L': Lower triangular

TRANS

TRANS is CHARACTER*1. Specifies the operation applied to A.

  • = 'N': A * X = B (No transpose)
  • = 'T': A**T * X = B (Transpose)
  • = 'C': A**H * X = B (Conjugate transpose = Transpose)

DIAG

DIAG is CHARACTER*1. Specifies whether or not the matrix A is unit triangular.

  • = 'N': Non-unit triangular
  • = 'U': Unit triangular

N

N is INTEGER. The order of the matrix A. N >= 0.

NRHS

NRHS is INTEGER. The number of right hand sides, i.e., the number of columns of the matrices X and B. NRHS >= 0.

A

A is DOUBLE PRECISION array, dimension (LDA,N). The triangular matrix A. If UPLO = 'U', the leading n by n upper triangular part of the array A contains the upper triangular matrix, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading n by n lower triangular part of the array A contains the lower triangular matrix, and the strictly upper triangular part of A is not referenced. If DIAG = 'U', the diagonal elements of A are also not referenced and are assumed to be 1.

LDA

LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,N).

X

X is DOUBLE PRECISION array, dimension (LDX,NRHS). The computed solution vectors for the system of linear equations.

LDX

LDX is INTEGER. The leading dimension of the array X. LDX >= max(1,N).

B

B is DOUBLE PRECISION array, dimension (LDB,NRHS). The right hand side vectors for the system of linear equations.

LDB

LDB is INTEGER. The leading dimension of the array B. LDB >= max(1,N).

WORK

WORK is DOUBLE PRECISION array, dimension (N).

RESID

RESID is DOUBLE PRECISION. The maximum over the number of right hand sides of norm(op(A)*X - B) / ( norm(op(A)) * norm(X) * EPS ).

👑 Author

  • Univ. of Tennessee
  • Univ. of California Berkeley
  • Univ. of Colorado Denver
  • NAG Ltd.

Definition at line 148 of file dtrt02.f.

👑 Author

Generated automatically by Doxygen for LAPACK from the source code.

That’s the whole page, bestie. LAPACK version 3.12.0, manual page TESTING/LIN/dtrt02.f(3). 💅✨

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